The design principle of the airless bottle is based on atmospheric pressure, while very dependent on the pumping force of the pump set, the pump set should have excellent one-way sealing performance, blocking the air back into the bottle, resulting in a low-pressure state inside the bottle. When the difference between the low-pressure area and the atmospheric pressure inside the bottle is greater than the friction between the piston and the inner wall of the bottle, the atmospheric pressure will push the large piston inside the bottle to move. Therefore, the large piston cannot fit too tightly with the inner wall of the bottle, otherwise, the large piston will be unable to move forward due to excessive friction; on the contrary, if the large piston fits too loosely with the inner wall of the bottle, it is easy to have leakage, so the vacuum bottle has very high requirements for the professionalism of the production process.